This invention relates to an improved packer for oil and gas wells. More specifically, the invention relates to an improved retrievable compression set straddle packer assembly for cleaning operations in oil and gas wells.
In many types of oil and gas wells it is desirable to inject into the perforations in the casing in the well bore to remove debris and produced materials therefrom to allow formation fluids and gases to freely flow into the well bore. Typically, such injecting operations have been performed using a retrievable packer having frusto-conical type cups thereon to isolate the perforations to be washed. However, such cup-type packers are susceptible to damage of the frusto-conical cups as they pass over the perforations in the casing, pass through dry casing or pass through casing liners and cannot be used with high differential fluid pressures acting across the frusto-conical cups to prevent the cups from being damaged.
Therefore, in certain instances, it is desirable to have a retrievable compression set straddle packer assembly having two sets of compression set packer elements thereon to isolate perforations in the casing in the well bore for washing.
Also, it is desirable to have such a retrievable compression set straddle packer assembly to use as a selective injection packer to isolate portions of the well bore for fluid injection operations where the length of the packer assembly between the compression set packer elements may be easily varied for use in a wide variety of well operations.